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Browse Prior Art Database

Dynamic Intrusion Detection for Secure Access Enclosure

IP.com Disclosure Number: IPCOM000105078D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 114K

Publishing Venue

IBM

Related People

Double, GP: AUTHOR

Abstract

Enclosures that protect sensitive data, sensitive hardware, or valuable assets require some means of authorized access, while denying access to unauthorized persons. Physical locks are often easily picked. Access doors or drawers may also be opened by authorized but dishonest personnel, where no means is provided for recognizing intrusion. Tamper responding mechanisms are more secure because the system is capable of responding with an alarm and/or by recording the event for later auditing. Tamper responding mechanisms can be easily deactivated if they are only powered by external means. Tamper responding systems powered internally by batteries typically consume power and require careful design to minimize the battery load.

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Dynamic Intrusion Detection for Secure Access Enclosure

      Enclosures that protect sensitive data, sensitive hardware, or
valuable assets require some means of authorized access, while
denying access to unauthorized persons.  Physical locks are often
easily picked.  Access doors or drawers may also be opened by
authorized but dishonest personnel, where no means is provided for
recognizing intrusion.  Tamper responding mechanisms are more secure
because the system is capable of responding with an alarm and/or by
recording the event for later auditing.  Tamper responding mechanisms
can be easily deactivated if they are only powered by external means.
Tamper responding systems powered internally by batteries typically
consume power and require careful design to minimize the battery
load.  Internal sensors, such as microswitches in a simple on/off
circuit are often easily defeated by separating the sensor from its
detection circuitry.  The article describes an improved tamper
resistance device which provides information on the opened or closed
state of the access door or drawer.

      Commercially available Wiegand sensors have been used for
automotive and machine control applications.  A Wiegand sensor
consists of a specially processed magnetic material which is capable
of suddenly switching its magnetic moment when the material is
exposed to an external magnetic field intensity that exceeds a
critical threshold.  An inductor coil in close proximity to the
special material will produce an inductive pulse (Fig. 1) each time
the critical threshold is exceeded.  A commercially available option,
the basic Wiegand sensor provides a permanent magnet in conjunction
with the sensor.  The permanent magnet will alter its field in one
direction, thereby producing a positive pulse, and then in the
opposite direction as the ferrous material moves away, which produces
a negative pulse.

      Fig. 2 presents a self powered sensor consisting, in part, of a
commercially available Wiegand sensor 1 (with internal inductive coil
and permanent magnet) and a series resistor 2, both of which may be
integrated within a sealed sensor package 3, hereafter called sensor
3.  Sensor 3 is mounted in a secured enclosure 4, illustrated in Fig.
3, such that when the enclosure door 5 is closed, the door is in
physical contact with sensor 3.  The word "door" will be understood
to also mean "drawer" or "access panel".  Door 5 is presumed to be
made of ferrous material or contain a ferrous plate.

      Door 5 (or the door-mounted ferrous plate) is in close
proximity to the Wiegand sensor, such that the permanent magnet
associated with Wiegand sensor 1 alters its magnetic field to be
above the critical magnetic field intensity needed to produce a pulse
from the sensor.  In this configuratio...